Punch and die



PUNCH AND DIE 2 Sheets-Sheet 1 Filed Nov. 1. 1957 M Mm a H D. M W aw ArroRme-rs July 7, 195 J. D. THOMPSON PUNCH AND DIE 2 Sheets-Sheet 2 Filed Nov. 1, 1957 INVENTOR. J??? D. Tl/OMPS r nd I 4 M4 4 rrokms s 2,893,489 PUNCH AND DIE:

Jay D. Thompson, St. Paul, Application November 1, 1951, Serial No. 694,035

2 Claims. 01. 164-118) The invention herein has relation to a punch and die construction which has been devised to be especially usefullfor the purpose ofperforating polyethylene film and other tough, shear-resistant sheet materials. 7

- Sheet materials having perforationstherein are commonly in use. They are employed for many purposes, as. to produce containers: for vegetables, etc. To besuit- :UH Ed sw s at-enfo 2,893,489 Patented July 7, 1959 2 intermediate portion of said die, an externally threaded supporting member 17 for the die integral with and at a side of the body member, and a hollow frusto-conical element 18 integral with and at a side of said body member opposite the supporting member. The body and supporting members and the hollow frusto-conical ele- V ment are in alinement longitudinally of the die, and the outer end 19 of said frusto-conical element is in a plane perpendicular thereto. The externalthread of the supporting member 17 is to be screwed into a stationary lower member of a machine to incorporate the die. Said die could, however, be suitably and conveniently fixed in a machine, as for adjustment in a horizontal plane, in any ordinary or preferred manner.

The hollow frusto-conical element 18 is constituted as a wall of uniform thickness provided with parallel, cirablefor most purposes sheet'mater'i'als are required to be tough and shear-resistant. By way of example, polyethylene filmhas qualities which render it sufliciently tough and shear-resistant to be suitable for a variety of uses. Punches and dies. heretofore employed to accomplish cumferentially'spaced, longitudinally extending slots, each cylindrical in direction transversely of said frusto-jc'onical perforation of sheet materials, such as polyethylene film,

having high shear-resistant properties have been expensive to produce and short lived. In practice, sheet material is spread,o ut over-a surface andtpunches and dies for perforating the sheet material are arranged in banks or gangs. Customarily, the punches are constituted as balls which strike, hammer blows against the dies. Close and accurate constant alinement is required. Regardless of precautions which 'may be taken, thepunches and dies element or wall. Desirably, each slo't 20 can be of, or approach, zero width at the location of the outer end 19 of the frusto-conical element, or wall. The part-cylindrical elongated bars'21 are of uniform width, as well as of uniform thickness, andall longitudinally extending lines of said elongated bars are, geometricallyflspeaking,

shortly f become'out of =alinement, damaged 'and unfit for use.

The purpose of the present invention is to provide an inexpensive, new and improved punch and die construction which will be an improvement over punches and dies for the same general purpose heretofore known and will perform its intended service in eificient and satisfactory manner for an indefinitely long period of time.

'In the accompanying drawings forming a part of this specification,

Fig. l is an elevational view, partially in section and partially broken away, of a punch and die construction made according to the invention as when applied to use;

Fig. 2 is a plan view of a sheet of material having perforations therein as they might appear when made by the punch and die construction;

Fig. 3 is an enlarged side elevational view, partially broken away, of the punch and die of Fig. 1;

Fig. 4 is a central longitudinal sectional view of the punch and die;

Fig. 5 is a view corresponding with the disclosure of Fig. 4, but showing the punch in a difierent position;

Fig. 6 in an end elevational view of the die as it would appear from the position of line 66 in Fig. 3; and

Fig. 7 is a sectional view, taken as on line 7-7 in Fig. 5.

Referring to the drawings, 10 denotes a machine suitably and conveniently supporting a reciprocatable punch 11 and a stationary die 12 in vertical alinement, and 13 represents generally mechanism for causing the punch to be reciprocated. Desirably, the punch and die construction can be of steel. In practice of the invention, punches and dies such as 11 and 12 can be arranged in banks or gangs to be concurrently operable on sheet material, such as 14, between the punches and dies and rested on the dies, thus to produce perforations, such as 15, in the sheet material.

The die 12 is constituted as a body member 16 at an straight. I A, V

The internal and external "surfaces defining the inner and outer circumferences, respectively, of the part-cylindrical elongated-bars 21 are in concentric relation, and the outer end portions of the internal surfaces of said part-cylindrical elongated bars are in perpendicular rela tion to the outer end 19 of the frusto-conical element or wall 18 and provide therewith part-circular severing edges, each represented 22.

The part-cylindrical elongated bars 21, provided by the hollow frusto-conical element or wall 18, will be of structure and thickness to be sufl'iciently rigid to properly perform their intended service and yet flexible outwardly at their upper end portions in response to forcible insertion of a punch, such as 11, into the die.

A confining ring or annular element 23 on the external surface of the hollow frusto-conical element or wall 18 is for adjustably altering the tension of the outer end portions of the part-cylindrical elongated bars 21. Said part-cylindrical elongated bars will be under minimum tension when unconfined. The confining ring or annular element will be moved inwardly along the external surface of the frusto-conical element or wall 18 when tension of the part-cylindrical elongated bars is to be increased, and vice versa. There will be no confinement of the hollow frusto-conical element or wall when the ring or annular element is at its lowermost position. Said ring or annular element need be employed merely to adjust tension. The die is operative without a means for altering tension. In many instances of use, the bars 21 need not be under tension. Clearly, the amount of tension existent at the outer end portions of said part-cylindrical elongated bars can be adjusted to be that which is appropriate in any particular instance merely by sliding of the confining ring or annular element longitudinally of the hollow frusto-conical element or wall.

The punch 11 is constituted as an elongated cylindrical member to be forcibly slid into the outer end portion of the die 12. A tapered free end portion 24 of the punch meets the body thereof to provide an annular severing edge 25 in a plane perpendicular to the punch body and complementary to the part-circular severing edges 22 of the part-cylindrical elongated bar 21 of the die. The body of the punch must be somewhat larger than the die opening at the outer end 19 of the frlustoconical element or wall 18 when the part-cylindrical elongated bars 21 are in their natural, unflexed condition and said die is unexpanded. The free end portion of the punch is of reduced diameter to permit its entry into the die even though the punch and die may be somewhat out of longitudinal alinement.

A stripper '26 is for insuring that the punch will be moved clear of the sheet material each time the punch is returned to inoperative position.

In Fig. 3 of the drawings, the punch is disclosed as when in inoperative position, .and the die is unexpanded. Also see Fig. 6. In Fig. 4 the punch has entered the die to an extent where the circular severing edge 25 of said punch and the part-circular severing edges 25 I of the part-cylindrical elongated bars 21 of the die have cooperated to cut a blank from the sheet material, save for minute thread-like portions possibly occasioned by reason of absence of cutting action at the locations of the slots 20. In Figs. 5 and 7 the punch has reached its maximum depth in the die and the die has become expanded. The punch has been made to enter the die sutfi'ciently far to insure that thread-like portions, if any,

.the part-cylindrical elongated bars of the die permits efficient operation even when the punch and die may be misalined. Punch and die constructions made according to the invention can be inexpensively produced and 4 will be efficiently operable for indefinitely long periods of time.

While the punch and die construction as illustrated and described is for producing circular perforations, it can be employed to produce apertures of various shapes.

What is claimed is:

1. The combination with a female element constituted as a die of rigid material consisting of a supporting member and flexible elongated bars integral with and extending outwardly from said supporting member in adjacent relation to each other, side edges of outer end portions of said elongated bars which are in adjacent relation being tensioned into engaged relation with each other, said outer end portions and outer ends of internal surfaces of the elongated bars together defining a closed punch receiving opening and providing a circumferentially extending severing edge in bounding relation to said opening, of a male element constituted as apunch consisting of a body member to be forcibly inserted into the opening provided by said elongated bars and including a circumferentially extending severing edge complementary to the severing edge of the elongated bars, there being a divergent surface adjacent to and disposed exteriorly of the severing edge of one of said elements and :the outer end portions of said elongated bars being capable of flexing away from each other in response to forcible insertion of said punch into said die.

2. The combination as specified in claim 1, and means for adjusting tensionupon the outer end portions of said elongated bars.

References Cited in the file of this patent UNITED STATES PATENTS 1,142,627 Robinson June 8, 1915 2,288,308 Williams June 30, 1942 2,308,953 Brown Jan. 19, 1943 2,626,667 Spiller Jan. 27, 1953 

